Not believing the science is no excuse for failing the exam, otherwise you run into this sort of senario:
"Why did you get such bad results in your biology test?"
"Ah well you see it's my religious belief that disease is caused by immorality and not germs, so that is exactly what I wrote in the exam. It's not fair that they should penalise me for my religious beliefs"
Actually, you're comparing apples and oranges. Microbiological creatures are not a matter of opinion. They are testable, verifiable, falsifiable, etc.
Evolution on the other hand is not.....it is opinion. Imo, probably best for a philosophy class.
For what it's worth, following the Judeo-Christian teachings regarding immorality will prevent any number of diseases.
The CDC says that total abstinence is the only method that when fully practiced results in zero infection and zero pregnancy.